Rust stains can are an awful stain to have on your carpet especially if your carpet is a light color. But not to worry, these stains are not permanent and can easily be removed. Just have patience and carefully follow the directions that I have provided here for you with these two methods you can try.
Using a dull knife, scrape away as much of the rust from the carpet as possible. Next, fill a spray bottle with lemon juice. You can use fresh squeezed lemon juice or bottled lemon juice. Generously spray the affected area. Allow the lemon juice to sit for about 5 minutes and then blot the area with a white towel or paper towel. Make sure you do not rub the stain. Rubbing the stain will cause it to spread. Always blot the area by starting in the outer parts of the stain, making your way in to the center. If the lemon juice has no effect on the stain, make a solution by mixing liquid dishwashing soap and water. Then, using a clean white towel blot the area with the solution and repeat this step until the stain has been removed. Using spray bottle spray water onto the affected area and blot with a clean cloth until the solution has been removed. When the area has been rinsed, blot dry, and then vacuum the carpet. It is very important to use a clean, white towel when treating the stained area; you want to avoid dyes from colored towels to transfer onto the carpet.
For this second method, also begin by removing as much of the rust as you can from the carpet. Next, saturate the stain with vinegar; carefully pour it onto the stain or to make things a little easier use a trigger sprayer. Use a dull knife and gently work the vinegar into the carpet, and let it sit for about 40 minutes. Next, use a clean white towel and blot the area. You will see how the rust transfers from your carpet onto your towel. Allow the carpet to dry for about 8 hours, and then rinse using a white towel dip it in water, and blot the area to remove the rest of the vinegar and rust. This should remove the entire stain from your carpet, sometime it depends how long the stain has been on the carpet and if it had been treated before.